Triethylenediamine (TEDA), also known as 1,4-diazabicyclo(2.2.2)-octane, is well known in the commercial market as a catalyst or co-catalyst in the production of polyurethane plastics, elastomers and foams. A number of methods are known in the art for preparing and isolating this compound as a product of commercially acceptable purity.
Typically, the TEDA is isolated from the reaction mixture as a white crystalline hygroscopic product containing a small amount of by-product amine compounds. The TEDA product is generally placed on the market for commercial users in drums of about 25 kg capacity.
With improved purification the synthesized TEDA product is recovered having less than about 500 ppm by-product organic amine impurities. It was found, however, that the purified commercial powdery crystalline TEDA product of this desired low content of organic amine impurities, when stored in commercial size drums for even short periods, particularly in a moderately warm environment, tended to develop a caking, or blocking problem. This bulk aggregation of the powdery crystals is believed the result of two factors, namely. (1) sublimation and crystallization of the TEDA molecules forming a bridge between adjacent particles and (2) hygroscopicity which also results in agglomeration of adjacent particles. This stored powdery product becomes very difficult to remove from the drum by pouring or scooping.
EP 0 209 720 A1 discloses that the flowability of stored TEDA is improved by admixing with a flow promoting amount of a salt, amide or ester derivative of a C.sub.8 -C.sub.22 fatty acid. Especially suitable flow promoting additives for TEDA are salts of stearic acid, particularly sodium stearate.
However, it has been discovered that such TEDA compositions containing sodium stearate at flow promoting levels (250 ppm), when dissolved in water with agitation, yield a foam on the solution surface.
Since the most common means of using TEDA as a catalyst in polyurethane and/or polyisocyanurate formulations is as a solution in water which is a blowing agent, it is of critical importance for customer acceptance of the TEDA product, that the resulting aqueous solution be a substantially clear, colorless solution. Since TEDA by itself will yield a clear, colorless. foamless solution, the customer will accept nothing less from a TEDA product containing a flow promoting additive. Foam on the surface of an aqueous TEDA solution may indicate to customers that the TEDA composition may adversely affect the polyurethane reaction or the final product.